Method for manufacturing surface acoustic wave device and inspecting instrument

ABSTRACT

In a tester for a surface acoustic wave device used as a filter for high frequency bands in the field of mobile communications, the tester includes: an electron gun generating an electron beam to be first electrons; a condenser lens for converging the electron beam on a substrate; an electron beam scanning portion for scanning the electron beam on the substrate; a secondary electron detector detecting second electrons generating from the substrate by irradiated first electrons; a substrate holder holding the substrate; and a conductive grounding tool which can contact the metal film. The grounding tool includes a contacting head. The grounding tool includes: a contacting head that can contact the grounding tool and the metal film; an arm portion arranged at the end of the contacting head; a shaft arranged at the other end of the contacting head, and rotating the arm portion. The substrate has a two-layer structure, which includes: a circular piezo-electric substrate including lithium tantalate (LiTaO 3 ); and a metal film including aluminum (Al) formed on the piezo-electric substrate.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an inspection method for amanufacturing process of a surface acoustic wave device used in thefield of mobile communications etc., and, more particularly, relates toan electrode line-width measurement method of the surface acoustic wavedevice, and a tester used therein.

[0003] 2. Description of the Related Art

[0004] The field of use of a surface acoustic wave device is expanding,and use of high frequency bands in the field of mobile communications isespecially increasing. The surface acoustic wave device is used as afilter for the high frequency bands. Center frequencies of passage bandsin the filter are mainly determined by two-physical characteristics,which are the thickness and the line-width of comb-shaped-electrodes ofsurface acoustic wave devices. For this reason, in product qualitycontrol of the surface acoustic wave devices, it is important toprecisely measure and inspect the line-widths of thecomb-shaped-electrodes.

[0005] As a line-width inspection method, the line-width of thecomb-shaped-electrodes is conventionally measured with an opticalmicroscope. However, for instance in a surface acoustic wave device forhigh frequency bands used in US-PCS (United States-PersonalCommunications Services), comb-shaped-electrodes have line-widths ofabout 600 nm, while a specification range of products is as small asseveral tens of nm. Accordingly, such an optical line-width measurementsystem is not applicable to the measurement of line-width of thecomb-shaped-electrodes in such surface acoustic wave device.

[0006] An existing instrument, which can measure up to about 600 nmline-width, in a line-width measurement system uses an electron beam.The line-width measurement system is used in inspection during amanufacturing process of semiconductor devices. The inventors used thiselectron beam line-width measurement system for the measurement of theline-width of surface acoustic wave devices. However, the line-width ofsurface acoustic wave devices could not be precisely measured with anelectron beam line-width measurement system.

DISCLOSURE OF INVENTION

[0007] Upon examination by the inventors, it became clear that thecauses of the difficulty in precisely measuring electrode line-widthwith the line-width measurement system using an electron beam werepyroelectricity and the insulation by the piezo-electric substrate usedas a substrate material in the surface acoustic wave device.

[0008] Pyroelectricity is a property whereby the polarization of thepiezo-electric substrate changes with temperature change, andpolarization charges are generated on the substrate surface. Due topyroelectricity of the piezo-electric substrate, the piezo-electricsubstrate is polarized after the manufacturing process with atemperature change. As a result, the surface of the piezo-electricsubstrate in which electrode parts are laminated becomes an anode.Therefore the surface attracted electrons are negatively charged. Inaddition, since the piezo-electric substrate is insulated, electrifiedelectrons cannot be diffused to the perimeter of the piezo-electricsubstrate. Hence, when the line-width is measured with the line-widthmeasurement system using an electron beam, the surface of thepiezo-electric substrate is charged. Consequently, since the charged-upelectrons repel the irradiated primary electrons, the beam cannot reachto the comb-shaped-electrodes and their proximity, so that the outlineof the comb-shaped-electrodes will be vague. Accordingly, it is apparentthat a highly precise measurement of the line-width is impossible due tothe charged-up state.

[0009] Then, in order to prevent the charged-up state, an ionizer and asoft X-ray irradiation instrument are incorporated into the line-widthmeasurement system. The ion-blowing irradiated electronic chargescharged with an opposite polarity by the surface charged-up electrons,and soft X-rays, were irradiated to the piezo-electric substrate, atwhich the surface acoustic wave devices are arranged.

[0010] However, the methods for irradiating the ion and the soft X-rayshave problems in that a long time is necessary for completely removingthe charged-up electrons. In addition, charge-up due to the irradiatedprimary electrons and the electrons polarized at the surface of thepiezo-electric substrate by heating due to beam irradiation formeasuring the line-width cannot be avoided. For these reasons, when thesame location is measured repeatedly, the measured line-width value maybe different.

[0011] An object of the present invention is to solve the aboveproblems. The present invention provides a method for manufacturing asurface acoustic wave device, which can be measured with high precisionand with a high rate of reproduction of the measured values.

[0012] In addition, another object of the present invention is toprovide a tester for a surface acoustic wave device, having highmeasurement precision, whereby shape measurement having a high rate ofreproduction of the measured values is possible.

[0013] In order to achieve the above-described purposes, a first featureof the present invention inheres in a method for manufacturing a surfaceacoustic wave device, the method comprising: (a) a step of depositing ametal film on a piezo-electric substrate; (b) a step of coating aphotosensitive resin film on the metal film; (c) a step ofphoto-exposing and developing the resin film, forming a photosensitiveresin pattern, and selectively exposing a part of the metal film; (d) astep of grounding the metal film using the exposed metal film as awindow for grounding; (e) a step of irradiating an electron beam to thepiezo-electric substrate, and measuring the resin pattern while themetal film is grounded; (f) a step of etching the metal film using thephotosensitive resin pattern as a mask, and forming a metal pattern; and(g) a step of removing the photosensitive resin pattern.

[0014] According to the first feature of the invention, by grounding themetal film on the piezo-electric substrate, and by measuring thephotosensitive resin pattern, electrification on the piezo-electricsubstrate can be prevented, and therefore the shape of thephotosensitive resin pattern can be measured with high reproducibilityand high precision.

[0015] A second feature of the present invention inheres in a method formanufacturing a surface acoustic wave device, comprising: (a) a step ofdepositing a metal film on a piezo-electric substrate; (b) a step ofcoating a photosensitive resin film on the metal film; (c) a step ofexposing and developing the resin film, and forming a resin pattern; (d)a step of etching the metal film using the resin pattern as a mask so asto form a metal pattern; (e) a step of removing the resin pattern; (f) astep of grounding a part of the metal pattern; and (g) a step ofirradiating an electron beam to the piezo-electric substrate, andmeasuring the shape of the metal pattern electrically connected to thegrounded part, when the part of the metal pattern is grounded.

[0016] According to the second feature of the invention, by groundingpart of the metal patterns, and by measuring the metal patternelectrically connected with the grounded part, electrification on thepiezo-electric substrate can be prevented, and therefore measurement ofthe shape of the metal patterns with high reproducibility and highprecision becomes possible.

[0017] A third feature of the present invention inheres in a tester,comprising: (a) an electron gun for generating an electron beam; (b) acondenser lens for converging the electron beam; (c) an electron beamscanning portion for scanning the electron beam; (d) a detector fordetecting secondary electrons generating from a measuring object byscanning of the electron beam; and (e) a grounding tool for connectingground electrical potential to a metal film as one of a film at theunder part of the measuring object, and the measuring object.

[0018] According to the third feature of the invention, by comprisingthe grounding tool in which the metal film is connected to groundingpotential, the electronic beam can be irradiated without storingelectrons on the piezo-electric substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019]FIG. 1A is a schematic view explaining the configuration of atester of a surface acoustic wave device according to an embodiment ofthe present invention.

[0020]FIG. 1B is a plane view corresponding to FIG. 1A.

[0021]FIG. 2 is a plane view explaining the positional relationshipbetween a grounding tool of the tester of the surface acoustic wavedevice and a piezo-electric substrate according to the embodiment of thepresent invention.

[0022]FIG. 3 is a plane view explaining an arrangement position of thepiezo-electric substrate of the surface acoustic wave device.

[0023]FIGS. 4A to 4C are sectional views explaining the method formanufacturing the surface acoustic wave device according to theembodiment of the present invention.

[0024]FIG. 5A is a plane view explaining the method for manufacturingthe surface acoustic wave device according to the embodiment of thepresent invention, following the step shown in FIG. 4C.

[0025]FIG. 5B is a sectional view along the VB-VB direction of FIG. 5A.

[0026]FIG. 6A is a plane view explaining the method for manufacturingthe surface acoustic wave device according to the embodiment of thepresent invention, following the step shown in FIG. 5A and FIG. 5B.

[0027]FIG. 6B is a sectional view along the VIB-VIB direction of FIG.6A.

[0028]FIG. 7A is a plane view explaining the method for manufacturingthe surface acoustic wave device according to the embodiment of thepresent invention, following the step shown in FIG. 6A and FIG. 6B.

[0029]FIG. 7B is a sectional view along the VIIB-VIIB direction of FIG.7A.

[0030]FIG. 8A is a plane view explaining the method for manufacturingthe surface acoustic wave device according to the embodiment of thepresent invention, following the step shown in FIG. 7A and FIG. 7B.

[0031]FIG. 8B is a sectional view along the VIIIB-VIIIB direction ofFIG. 8A.

[0032]FIG. 9A is a plane view explaining the method for manufacturingthe surface acoustic wave device according to the embodiment of thepresent invention, following the step shown in FIG. 8A and FIG. 8B.

[0033]FIG. 9B is a plane view explaining the method for manufacturingthe surface acoustic wave device according to the embodiment of thepresent invention, following the step shown in FIG. 9A.

BEST MODE FOR CARRYING OUT THE INVENTION

[0034] An embodiment of the present invention will be described withreference to the accompanying drawings. It is to be noted that the sameor similar reference numerals are applied to the same or similar partsand elements throughout the drawings, and the description of the same orsimilar parts and elements will be omitted or simplified. Generally, itwill be appreciated that the various drawings are not drawn to scalefrom one figure to another nor inside a given figure, and in particularthat the layer thickness are arbitrarily drawn for facilitating thereading of the drawings. In the following descriptions, numerous detailsare set forth such as specific signal values, etc. to provide a thoroughunderstanding of the present invention. However, it will be obvious tothose skilled in the art that the present invention may be practicedwithout such specific details.

[0035] As shown in FIG. 1A, a tester of a surface acoustic wave deviceaccording to an embodiment of the present invention includes an electrongun 1 for generating and irradiating an electron beam to provide primaryelectrons, a condenser lens 2 for converging the electron beam on thesubstrate 9, a scanning portion 2 for scanning the electron beam on thesubstrate 9, a secondary electron detector 4 for detecting secondelectrons generated from the substrate 9 irradiated by the primaryelectrons, a substrate holder 5 for holding the substrate 9, and agrounding tool 6. The grounding tool 6 is conductive and can be incontact with the metal film 7 on the measuring substrate 9. Thegrounding tool 6 includes a conductive contacting head 12, which can bein contact with the metal film 7, an arm portion 47 attached at the tipof the contacting head 12, and a shaft 48 arranged at the opposite sideof the contacting head 12 of the arm portion 47. Furthermore, the testerincludes a vacuum chamber 50 accommodating the electron gun 1 and thesubstrate 9, an picture formation unit 51 for forming a picture based onthe detected amount of the secondary electrons from each position on thesubstrate 9 on which the electron beam was scanned, and a criticaldimension measurement unit 52 for detecting the outline of thecomb-shaped-electrodes based on the formed picture, and measuring theline-width thereof.

[0036] In addition, the substrate 9 has a two-layer structure, whichconsists of a circular piezo-electric substrate 8 made of lithiumtantalate (LiTaO₃), and a metal film 7 made of aluminum (Al) formed onthe piezo-electric substrate 9. Lithium niobate (LiNbO₃) may be used asmaterials of which the piezo-electric substrate 8 made, instead ofLiTaO₃. The materials, which make the piezo-electric substrate 8, do notneed to be LiTaO₃ or LiNbO₃.

[0037] As shown in FIG. 1B, metal patterns for constituting the surfaceacoustic wave device 11 are formed by the metal film 7 (refer to FIG. 2for details of the metal patterns). The metal film 7 is disposed at aposition, which can provide contact with the grounding tool 6. Inaddition, an opening 10 for contact, formed in the metal part 7, is alsoarranged at a circumferential part of the substrate 9 which can alsocontact with the grounding tool 6.

[0038] As shown in FIG. 2, the grounding tool 6 is arranged in theposition 13 beside the substrate 9. The grounding tool 6 is movable onthe shaft 48 as a center thereof. The grounding tool 6 can move to theposition 46 where the contacting head 12 can contact the metal film 7,and to the position 14 where the contacting head 12 corresponds with theopening 10. The contacting head 12 is also movable so as not to contactwith the metal film 7 after measurement.

[0039] As shown in FIG. 3, the surface acoustic wave device 11 hasplural metal patterns consisting of the metal film 7. The metal patternsinclude comb-shaped-electrodes 24 and 27 for input,comb-shaped-electrodes 30 and 33 for output; bonding pads 22, 25, 28,and 31, reflectors 21 a and 21 b, and ground lines 15 to 20. Thecomb-shaped-electrodes 24, 27, 30, and 33, and the bonding pads 22, 25,28, and 31 are respectively connected to each other with connectionlines 23, 26, 29, and 32. In addition, the bonding pads 22, 25, 28, and31, and the metal film 7 on dicing lines are connected with the groundlines 16, 20, 17, and 19. The reflectors 21 a and 21 b, and the metalfilm 7 on the dicing lines are connected with the ground lines 15 and18.

[0040] For these reasons, the comb-shaped-electrodes 24, 27, 30, and 33,and the reflectors 21 a and 21 b, which are electrically connected tothe metal film 7 on the circumference region of the substrate 9 throughthe ground lines, have the same electric potentials.

[0041] In the following, a method for manufacturing the surface acousticwave device and an inspection method for the surface acoustic wavedevice according to the embodiment of the present invention will bedescribed.

[0042] (a) To begin with, the piezo-electric substrate 8 is prepared asshown in FIG. 4A. In addition, as shown in FIG. 4B, the metal film 7 isdeposited on the piezo-electric substrate 8 by sputtering. When aluminum(Al) alloys are used as a target, an Al alloy film as the metal film 7can be deposited on the piezo-electric substrate 8.

[0043] (b) Next, as shown in FIG. 4C, a photosensitive resin (a photoresist) 34 is spin coated on the metal film 7.

[0044] (c) Next, a photolithography process is carried out. Thephotosensitive resin film 34 is selectively exposed using mask patternsshaped such as comb-shaped-electrodes and reflectors. After exposure,the exposed parts of the photosensitive resin film 34 are selectivelyremoved by developing and rinsing, as shown in FIG. 5A and FIG. 5B, thusphotosensitive resin patterns 35 and 36 etc. are formed. Thephotosensitive resin pattern 36 is connected to the photosensitive resinfilm 34 through the photosensitive resin pattern 35. In addition, inthis photolithography process, the opening 10 is also formedsimultaneously. The photosensitive resin film 34 at the position of theopening 10 is removed in a developing process (the contacting head 12contacts with the metal film 7 inside of this opening 10, as shown inFIG. 6B.)

[0045] (d) Next, the shape of the photosensitive resin patterns ismeasured with the tester shown in FIG. 1A. First, the developedpiezo-electric substrate 8 is arranged on the substrate holder 5 insideof the vacuum chamber 50 of the tester. As shown in FIG. 6A and FIG. 6B,the grounding tool 6 is moved, and the contacting head 12 contacts themetal film 7 at a bottom of the opening 10. In the state where thecontacting head 12 of the grounding tool 6 contacts the metal film 7,the geometry of the photosensitive resin patterns including a line-widthof the resin pattern 36 of the surface acoustic wave device is measured.First, in order to get a picture of the photosensitive resin pattern 36,the electron beam 3 is irradiated to the substrate 9 as shown in FIG.1A. This irradiated electron beam 3 is equivalent to an electron beam 37shown in FIG. 6B.

[0046] (e) Next, it is judged whether the measured values are within therange of specifications. If a measured value is within the range of thespecifications, the process will advance to the next step. On the otherhand, if a measured value is outside the range of the specifications,and the photo resists such as photosensitive resin films 34 to 36 areremoved, and each process shown in FIGS. 4C to 6B may be repeated withadjusted exposure conditions. As thus described, since an accuratemeasurement is made possible, products that are outside the range of thespecifications can be prevented from advancing to the next process. As aresult, loss in processing can be reduced, and product yield can beimproved.

[0047] (f) Next, the grounding tool 6 is separated from the metal film7, and the piezo-electric substrate 8 is automatically taken out of thetester.

[0048] (g) The metal film 7 is etched using the photosensitive resinfilm 34 to 36 as a mask. The metal film 7 is made of, for instance,aluminum alloy, and anisotropic etching is performed by the reactivityion etching (RIE) method using a chlorine (Cl₂) based gas.

[0049] (h) Photo resists like the photosensitive resin films 34 to 36are removed by plasma ashing using oxygen (O₂) based gas. As a result,as shown in FIG. 7A and FIG. 7B, the metal patterns, such as a reflector21 a and the ground line 15, are formed on the piezo-electric substrate8. The metal pattern such as the reflector 21 a is electricallyconnected to the metal film 7 through the ground line such as the groundline 15.

[0050] (i) The line-widths of the patterns, such as the reflector 21 aformed on the piezo-electric substrate 8, are measured. The measurementis carried out in the same way as the shape measurement ofphotosensitive resin patterns. In this measurement, the position of themetal pattern 7 that contacts the contacting head 12 is different fromthe case measuring shape of the photosensitive resin patterns. That is,as shown in FIG. 8A and FIG. 8B, the grounding tool 6 is moved, and thecontacting head 12 contacts the position of the metal film 7electrically connected to the metal pattern that is a measurementobject, such the reflector 21 a. For this reason, the current 39 ofelectrons is formed.

[0051] (j) Next, it is determined whether measured values are within therange of the specifications. If the measured value is within the rangeof the specifications, the process can advance to the following step.

[0052] (k) The piezo-electric substrate 8 is diced, and it is split intoindividual surface acoustic wave devices 11. As shown in FIG. 9A, beforedicing, for instance, the metal patterns such as bonding pads 22 and 28are electrically connected to the metal film 7 on a dicing line 42through ground lines such as the ground lines 16 and 17. In dicing, thewidth of the dicing lines 40 to 43 are set more broadly than the widthof the metal film 7 in order to cut these electrical connections. Asshown in FIG. 9B, in the surface acoustic wave device 11, the groundlines 15 to 20 electrically connect the comb-shaped-electrodes 24, 27,30, and 33, and the reflectors 21 a and 21 b to the outer mostcircumferential part. In addition, in the case where the dicing line 44includes a part of the bonding pads 25 and 31 such as the dicing line 44shown in FIG. 9A, the bonding pads 25 and 31 serves as the metal film 7in the outer most circumferential part.

[0053] (l) Finally, die bonding, wire bonding, and packaging, etc. arecarried out on the surface acoustic wave devices 11; thereby the surfaceacoustic wave devices are completed.

[0054] As shown in FIG. 6A and FIG. 6B, the current 38 of electrons isformed when the contacting head 12 of the grounding tool 6 contacts themetal film 7. The current 38 of electrons includes: (a) electronscharged on the piezo-electric substrate 8 by temperature change in themanufacturing process; (b) primary electrons irradiated by the electronbeam; and (c) electrons further generated on the piezo-electricsubstrate 8 since the substrate 8 is further polarized by heating causedby the beam irradiation. The current 38 runs from the metal film 7 intofinally the grounding tool 6 so as to reduce an incline of electricalcurrent potential. The current 38 suppress to accumulate electrons onthe piezo-electric substrate 8 in resin patterns such as thephotosensitive resin pattern 36, which are used as a measurement objectand in proximity of the patterns. Consequently, a trajectory of theelectron beam 37 is not deflected, and highly precise and reproduciblemeasurements of the shape of photosensitive resin patterns are possible.

[0055] The line-width of the comb-shaped photosensitive resin patternwas respectively measured with the tester according to the embodiment ofthe present invention and with a conventional line-width-measurementsystem without the grounding tool 6, and the result was compared. As aresult of measuring the 500 nm line-width of the comb-shapedphotosensitive resin pattern 30 times, a standard deviation value wasabout 1 nm by the measurement method according to the embodiment of thepresent invention. On the other hand, a standard deviation was about 5nm by the conventional measurement method without the grounding tool 6.This demonstrated that highly precise and highly reproduciblemeasurements are possible using the measurement method according to theembodiment of the present invention.

[0056] In addition, as shown in FIG. 8A and FIG. 8B, in a state wherethe contacting head 12 of the grounding tool 6 is in contact with themetal film 7, the current 39 of electrons includes: (a) electronsfurther charged on the piezo-electric substrate 8 by polarization due totemperature change in the manufacturing process; (b) primary electronsirradiated by the beam; and (c) electrons further charged on thepiezo-electric substrate 8 by heating caused by irradiation. The flow 39of electrons runs from the metal film 7 into the grounding tool 6through the ground line 15 so as to reduce an incline of electricalcurrent potential. The flow 39 stops electrons from accumulating in thepiezo-electric substrate 8 of the metal film 7, such as the reflector 21a used a measurement object, and in proximity to the object.Accordingly, a trajectory of the electron beam 37 is not deflected, andhighly precise and reproducible measurements of the shape ofphotosensitive resin patterns become possible.

[0057] The line-width of the comb-shaped-electrode, which is a metalpattern, was measured with the tester according to the embodiment of thepresent invention and with the conventional line-width-measurementsystem without the grounding tool 6 respectively, and compared. As aresult of measuring the comb-shaped-electrode having a 500 nm line wide30 times, the standard deviation value was about 1 nm by the measurementmethod according to the embodiment of the present invention. However,the standard deviation was about 5 nm by the conventional measurementmethod without the grounding tool 6. This demonstrated that highlyprecise and highly reproducible measurements are possible using themeasurement method according to the embodiment of the present invention.

[0058] In addition, in the embodiment of the present invention, ameasurement in a case where the line-width of both the resin patternsand the metal patterns is less than or equal to 2.0 μm and more than0.35 μm is possible.

[0059] In addition, when the reflector is measured, since the reflectoris easier to ground than the comb-shaped-electrode, the shape of thereflector can be measured more precisely. This is because, for instance,in a case where the reflector 21 a is measured, the reflector 21 a,directly connected to the ground line 15, becomes charged less easilythan the comb-shaped-electrode 24, which is far from a ground line.

[0060] The present invention may be embodied in other specific formswithout departing from the spirit or essential characteristics thereof.The embodiments are therefore to be considered in all respects asillustrative and not restrictive. It will be obvious to those skilled inthe art that various embodiments of the present invention may bepracticed.

[0061] For example, materials and quantity of material parts are in oneof the embodiments of the present invention. Even if other materialsreplace these materials, technical effectiveness does not change. Forexample, technical effectiveness does not change when lithiumtetraborate (LiB₄O₇) is used as a piezo-electric substrate.

[0062] In addition, in the embodiment of the present invention, thegrounding tool 6 may further include other elements, like a clampportion (a spring portion) holding the contacting head 12 in thesubstrate 9, and a drive portion rotating the shaft 48. Furthermore, thegrounding tool 6 may further have a portion moving the arm portion 47from top and bottom and right and left.

[0063] In addition, in the embodiment of the present invention, themetal film 7 based on Al is deposited on the piezo-electric substrate 8.Here, effectiveness is not changed even in a case where the metal filmconsisting of materials different from Al is deposited on thepiezo-electric substrate 8 and in a case of a multi-layer structurehaving different laminated materials. In addition, the type and shape ofa photosensitive resin pattern and a metal pattern are not particularlylimited, for instance, like comb-shaped patterns. Furthermore, in theembodiment of the present invention, the line-width of thephotosensitive resin pattern and the line-width of thecomb-shaped-electrode of the metal patterns are measured. Here forexample, the line-width and the shape are positions, such as thephotosensitive resin pattern 35 and the reflector 21 a, which arenecessary in quality control may be measured and checked. Furthermore,the number of times of measurement can be performed is not particularlylimited.

[0064] For these reasons, it is obvious that the present inventionincludes various embodiments, which have not been described above.

1. A method for manufacturing a surface acoustic wave device,comprising: a step of depositing a metal film on a piezo-electricsubstrate; a step of coating a photosensitive resin film on the metalfilm; a step of exposing and developing the photosensitive resin film,and forming a photosensitive resin pattern, and selectively exposing apart of the metal film; a step of grounding the metal film using theexposed metal film as a window for grounding; a step of irradiating anelectron beam to the piezo-electric substrate, and measuring thephotosensitive resin pattern when the metal film is grounded; a step ofetching the metal film using the photosensitive resin pattern as a mask,and forming a metal pattern; and a step of removing the photosensitiveresin pattern.
 2. The method according to claim 1, wherein theline-width of the resin pattern is less than 2.0 μm and more than 0.35μm.
 3. The method according to claim 1, wherein the piezo-electricsubstrate consists of one of lithium tantalate (LiTaO₃), and lithiumniobate (LiNbO₃).
 4. The method according to claim 1, wherein the metalfilm is grounded by contacting a contacting head of a grounding toolwith the exposed metal film.
 5. The method according to claim 1, whereinwhether the measured photosensitive resin pattern is within a range ofspecifications is determined after the step of measuring the shape ofthe photosensitive resin pattern.
 6. The method according to claim 4,further comprising: a step of grounding the metal film electricallyconnected to the metal pattern by contacting the contacting head of thegrounding tool with the metal film, after the step of removing the resinpattern; and, a step of irradiating the electron beam to thepiezo-electric substrate, and measuring the shape of the metal patternwhen the metal film is grounded.
 7. A method for manufacturing a surfaceacoustic wave device, comprising: a step of depositing a metal film on apiezo-electric substrate; a step of coating a photosensitive resin filmon the metal film; a step of exposing and developing the photosensitiveresin film, and forming a resin pattern; a step of etching the metalfilm using the photosensitive resin pattern as a mask so as to form ametal pattern; a step of removing the photosensitive resin pattern; astep of grounding a part of the metal pattern; and a step of irradiatingan electron beam to the piezo-electric substrate, and measuring theshape of the metal pattern electrically connected to the grounded part,when the part of the metal pattern is grounded.
 8. The method accordingto claim 7, wherein the line-width of the metal pattern is less than 2.0μm and more than 0.35 μm.
 9. The method according to claim 7, whereinthe piezo-electric substrate consists of one of lithium tantalate(LiTaO₃), and lithium niobate (LiNbO₃).
 10. The method according toclaim 7, wherein whether the shape of the measured metal pattern iswithin the range of specifications is determined, after the step ofmeasuring the shape of the metal pattern.
 11. The method according toclaim 7, wherein the metal patterns, used as a shape measurement object,are patterns of a reflector.
 12. A tester, comprising: an electron gungenerating an electron beam; a condenser lens converging the electronbeam; an electron beam scanning portion for scanning the electron beam;a detector detecting secondary electrons generated from a measuringobject by scanning of the electron beam; and a grounding tool connectingground electrical current potential of a metal film as one of a film ata under part of the measuring object, and the measuring object.
 13. Thetester according to claim 12, wherein the grounding tool comprises: acontacting head configured to contact the grounding tool with the metalfilm; an arm portion arranged at one end of the contacting head; a shaftarranged at the other end of the contacting head, and configured torotate the arm portion.
 14. The tester according to claim 13, furthercomprising a holder holding a sample provided the metal film.
 15. Thetester in scope of claim 13, further comprising a vacuum chamberconfigured to receive the electron gun and the measuring object therein.16. The tester according to claim 13, further comprising a pictureformation unit forming a picture based on amounts of the detectedsecondary electrons.
 17. A tester according to claim 16, furthercomprising a critical dimension measurement unit measuring the shape ofthe measuring object based on the picture formed by the pictureformation unit.